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The steady two-dimensional flow of a horizontal heat pipe in vapor region is investigatednumerically. For study of heat transfer and fluid flow behaviors of the heat pipe, the governingequations in vapor region have been solved using a finite difference method. The numerical resultsof heat transfer and fluid flow are presented for Reynolds numbers ranging of (Re =4, 10), thePrandtl number taken is (Pr=0.00368), and the pipe dimension is taken to be (L/R =5). The resultsshow that the stream function at the wall increases linearly in the evaporator, decreases linearly inthe condenser and is steady in the adiabatic region because of uniform inflow and outflow boundaryconditions. Also, it can be seen that as the Reynolds number increases, the pressure distributionsshift up without considerable change in their shapes. The numerical analysis have shown that for thelow and moderate Reynolds number, the shear stress becomes zero at a point very close to the endof the condenser. For verification of current model, the results of stream function for a heat pipehave been compared with the previous study at the same boundary conditions and a good agreementhas been noticed.

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In this paper a novel technique proposed and implemented practically for photovoltaic cell efficiency enhancements. It is known that Iraq is one of the hottest countries in the world. It has a solar insolation average and energy higher than that of most of other countries. Solar photovoltaic cell has a limited efficiency boundary, which is affected by the amount of absorbed solar heat (energy). It is found that; when the solar array temperature excess 70 C0, the photovoltaic solar cell efficiency will be decreased remarkably. This novel technique which include painting the solar cell surface with chlorophyll only one time and painting it’s surface with chlorophyll and polymer mixture another time gives a perfect solution to get a wide band of solar temperature array with a remarkable efficiency enhancement. The experimental results show that coating solar cell surface with chlorophyll only increases its efficiency by 5.5 % which is the maximum increase, while coating solar cell surface with chlorophyll and polymer mixture increases its efficiency by 3.1 % only.which is less than increase in the first case but more than that of solar cell without coating. All cells tested at constant solar irradiation (I=1000 W/m^2), and variation of temperature in range (30 oC to 80 oC).

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Due to depleting traditional energy resources, solar energy appears a promising alternative renewable preference for many demonstrational applications including solar desalination plants. In this respect, an experimental study on the performance of pre-designed and manufactured Lab-scaled water desalination used parabolic trough solar collector PTC was carried out for the first time in Al-Najaf City-Iraq (32° 1' N / 44° 19' E). The proposed designed is to enhance the production of the water still by integrated with a parabolic trough solar. The used PTC with 90o-rim angle mirrored reflector that focused the sun on its focal line of a copper tube with black chrome coating receiver. Primary results reveal 11% improvement in system efficiency is obtained over the used vacuumed copper tube with black chrome coating receiver. Results also confirm PTC facing North or South positions is best for maintaining better system efficiency.

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Silicon solar cells are one of the broadest sources of clean energy. One of the big problems we face is the low efficiency of solar cells due to high temperatures and therefore this problem was addressed using materials that help to resisting high temperatures and increasing the efficiency. This research study the electrical properties for Silicon solar cells, and focused on enhance the efficiency for these solar by adding an active layer sensitive to the light which is consist of mixture of polymer (Nitro Cellulose) and blue fluorescent dye named victoria where the blue dye work on Expansion of absorption range and the polymer Resists high temperatures. The experimental sequels represent that painting the cell surface with blue dye (victoria) increase the amount of efficiency by (0.673 %).The solar cells was tested under steady intensity of irradiation (I=1000 W/m^2), and variety of temperatures in range ( 33-70 ).

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In the present work, a numerical procedure to study the effect of the triangular windbreak on the drag forces of the parabolic trough collector (PTC) provided. Windbreaks are useful tools to reduce drag force. While common windbreaks are vertical walls, present work suggested an alternative triangular shaped hill put in the mainstream of flow. COMSOL Multiphysics v. 5.3 code used in the analysis of the trough solar collector. The results show that a reduction in drag forces may reach 55% of the original case (no-windbreak usage). Five different values of wind flow have been analyses. To achieve this aim, a 2D modelling of trough solar collector was carried out. The current work is the continuous work of the authors of studying the effect of windbreaks on troughs.

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Desalination using solar energy systems is a practical solution for production of potable water and particularly in remote areas, which suffer from lack of drinking water due to poor infrastructure. It is possible for a small distillation system to be a practical and economical solution for current and future demand for potable water with availability water resources and large amounts of solar radiation. Therefore, productivity that could be increased by increasing the model's ability to store the heat energy needed to maintain evaporation was discussed using nanoparticles dispersed in paraffin wax beneath the basin. In this paper, the main objectives of the study are to obtain the optimum parameters of PCM mass, NPCM mass, water mass and solar radiation to give the best productivity of the model inside the atmosphere of Najaf city, a numerical study involving the study of the performance of single-slope solar still using different masses of PCM with and without nanoparticles. Nanoparticles is used to improve thermal conductivity of paraffin wax. The most commonly used paraffin wax (PCM) and Al2O3 (nanoparticles) complements its specific thermal properties with fusion temperature where the main active properties are studied. The numerical solution was done using COMSOL 5.3 software and the results were compared with previous studies and showed that a good agreement. Also, the results showed that the use of 1 kg of PCM represent optimal amount of enhancement, and thus using of 3 Vol.% concentration of Al2O3 nanoparticles dispersed in 1 kg of paraffin wax gives the possibility of improving the traditional single slope solar still daily productivity by about 20%.

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Flat Plate collector is the most common type of solar water heater, due to its low price, easy installation, and long life. The efficiency of a solar collector is key to evaluating its performance in thermal facilities, especially applications requiring low or medium temperatures. The most important factors affecting the efficiency of the solar collector are the weather conditions, the design of the collector, the type of work fluid used. A Flat plate collector tested experimentally in solar heating system worked by direct flow and closed system to heating space in Najaf, Iraq (32° 1' N / 44° 19' E). Experimental results showed that the overall daily efficiency of the collector reached 37.16%. Moreover, the maximum temperature of hot water for collector reached 57.1oC

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Dye sensitized solar cells (DSSC) are placed in third generation of solar cells. DSSC have more benefits over silicon solar cells such as low fabrication cost and eco-friendliness. In the existing research work dye-sensitized solar cells were fabricated using natural dye extracted from some fruits as ‘sensitizer’. The TiO2 thin films were prepared on FTO coated glass substrate using doctor blade technique as photoanode. The fruits and plants dye extracted in ethanol was used as sensitizes. The standard polymer electrolyte with counter electrode of platinum was used and natural DSSCs were fabricated. The optical properties of FTO coated thin film and extracted dyes were studied using UV–VIS-NIR spectroscopy. The extracted fruits and plants dye showed absorption up to 500 nm wavelength of incident light. The fabricated solar cells were characterized for electrical properties through Keithley source meter which are current, fill factor, open circuit voltage was achieved. Results showed that fruits and plants dyes using in DSSCs can be the promising source as light harvester.

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The Using of desalination technology to meet The demand for fresh water production and that is increasing day by day is due to the increase in world population and with industrial growth . Among technologies used for desalination, Solar stills are easy to design, easy to maintain and low cost compared to other water systems . the same time, it has low productivity , But its disadvantages are low productivity, The aim of this paper is to provide a detailed overview of the various types of solar stills, passive and active design features, single and multi-function designs. And different efficiency improvements, The reflectors used, fins, heat storage, condensers, collectors, Also to improve heat and mass transfers. New advances in phase-change materials and nano composites Are highly promising for further performance development, Subsequent studies in these and other areas needs to be carried out to improve productivity of the solar distillers and take advantage of solar energy in this and other fields .

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Utilizing solar energy has received a giant activity by energy applications into distinctive states within the world. The sun is regarded strong supply providing uninterrupted coherent energy. In this research, simulation study has been done to estimate the performance of dual purpose solar collector (DPSC). Flat plate dual purpose solar collector with dimensions (194 cm length, 95 cm width and 14 cm thickness) has been used for heating the air and water for different using. Rectangular fins are used in air duct to increase heat transfer coefficient in air heater part. COMSOL Multiphysics 5.4 computer program has been used to calculate the theoretical results. Many parameters such as a different flow rate and temperatures for the inlet working fluids are investigated.

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Shrouding of HAWT in a flanged diffuser is among techniques of wind power augmentation especially in urban areas. In this paper, a small scale of Flanged Diffuser Augmented Wind Turbine (FDAWT) was presented with flanges angle (ϴf) of 0°. The rotor fit for FDAWT was designed based on a modified blade element momentum theory, which adopts on developing the preliminary rotor blade geometry in terms of pitch angle. The modification of the blade pitch angle was based on the maximum wind speeds in the empty flanged diffuser at rotor position along the blade sections. The models of rotor and diffuser were fabricated and experimented in the wind tunnel. The experimental tests were conducted to calculate the power at a different wind velocity ranged 5 - 9 m/s. The performance tests were in terms of power coefficient, CP and torque coefficient, CQ as a function of the tip speed ratio as well as maximum power as a function of the wind velocity. The results show the rate of increase in the maximum power producing for the FDAWT with the modified rotor up to 291% more than what it is for the preliminary bare HAWT, while this increase was only 257% for FDAWT with the preliminary rotor.

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It is notorious that the efficiency of the solar PV cell decreases with increasing temperatures, and cooling is indispensable at high lighting conditions or hot weather conditions. In this study, used nanocomposite material Titanium dioxide (TiO2) with polymer at different concentrations. This application shows very significant improvement in the PV efficiency and solar radiation antireflection. The PV Polycrystalline solar cell was coated to increase the excitation process of the electron to the sunlight also to reduce the infrared radiation (IR) absorbed in low frequency. From the experimental test, one and two layers of polymer and Titanium dioxide composite show high performance. Where get for the first concentration (CO1) with one layer and two layers increase the efficiency by 1.11% and 2.71%, respectively. While when using the second concentration (CO2), get the increase in efficiency about 0.473% and 1.59% for one and two layers of coating, respectively.